Integration of thin film resistors having different TCRs into single die

ABSTRACT

An integrated circuit structure including multiple thin film resistors having different sheet resistances and TCRs includes a first oxide layer ( 2 ) formed on a semiconductor substrate ( 1 ), a first thin film resistor ( 3 ) disposed on the first oxide layer ( 2 ), and a second oxide layer ( 14 ) disposed over the first oxide layer ( 2 ) and first thin film resistor ( 3 ). A second thin film resistor ( 15 ) is formed on the second oxide layer ( 14 ) and a third oxide layer ( 16 ) is formed over the second thin film resistor ( 15 ) and the second oxide layer ( 14 ). Interconnect metallization elements ( 12 A,B &amp;  22 A,B) disposed on at least one of the second ( 14 ) and third ( 16 ) oxide layers electrically contact the circuit element ( 4 ), terminals of the first thin film resistor ( 3 ), and terminals of the second thin film resistor ( 15 ), respectively, through corresponding contact openings through at least one of the second ( 14 ) and third ( 16 ) oxide layers.

BACKGROUND OF THE INVENTION

The present invention relates generally to practical thin film resistorstructures and methods for integrating multiple thin film resistors ofthe same or different sheet resistances and the same or differenttemperature coefficients of resistance, and to providing a practicalmeans of adjusting the temperature coefficient of integrated circuitcomponents.

Design engineers would be able to better optimize some integratedcircuit designs if it were practical and economical to integrate thinfilm resistors having various sheet resistances and TCRs (temperaturecoefficients of resistance) into a single integrated circuit structure.However, there has been no practical, economical way to accomplish thisbecause temperature processing cycles associated with forming subsequentthin film resistor layers subsequent to formation of a first thin filmresistor layer would cause a variety of difficult integrated circuitprocessing problems. For example, controlling the effect of variousthermal cycles on the sheet resistances and TCRs of the multiple thinfilm resistors formed on successive oxide layers may be very difficult.Also, the presence of metallization layers in integrated structuresincluding thin film resistors on multiple layers may make it verydifficult to design subsequent thermal cycles of the kind needed to becompatible with the thin film resistor properties. Design engineersfrequently find it desirable to use a resistor having a large positiveTCR to offset a negative TCR of a another circuit element. However,there has been no practical way of providing high-precision thin filmresistors having positive TCRs in typical integrated circuit structures.

U.S. Pat. No. 4,019,168 entitled “Bilayer of Thin Film Resistor andMethod for Manufacture”, issued Apr. 19, 1977 to Franklyn M. Collins,describes an integrated circuit structure including a layer of tantalumon a layer of nichrome for the purpose of stabilizing the sheetresistance of the nichrome. However, the foregoing patent is notdirected to issues regarding the TCR of thin film resistors.

It is conventional to adjust the thickness or sheet resistance of aresistive thin film layer by using suitable thermal anneal cycles toachieve a target sheet resistance and a target TCR for a deposited SiCrlayer. Empirical curves have been developed that represent therelationships between the TCR and sheet resistance of various resistivethin film materials as functions of various integrated circuitprocessing parameters, such as the type of resistive material, thermalcycle temperatures and durations, etc. Once the sheet resistance of athin film layer is known, the amount of annealing needed to increase itsTCR by a desired amount can be determined from the curves. However, thetechnique of using thermal cycles to obtain a TCR target value that isprecisely equal to zero or other value is not practical for somematerials and for some sheet resistances, especially for SiCr, andespecially for making very low resistance thin film resistors which arevery wide and very short and therefore are of substantially reducedaccuracy.

There is an unmet need for a practical method and integrated circuitstructure for providing various combinations of the same or differenthigh or low sheet resistances and the n same or different TCRs for twoor more thin film resistors, each on a different player.

There also is an unmet need for a practical technique for providing athin film resistor structure that can be used to offset the TCR ofintegrated circuit elements in which the TCR is not easily adjustableduring integrated circuit manufacture.

There also is an unmet need for a way of manufacturing more stable thinfilm resistors in an integrated circuit process.

There also is an unmet need for an integration technique for providingtwo accurate SiCr thin film resistors having different sheet resistancesand zero-value TCRs.

There also is an unmet need for an integration technique for providingtwo accurate SiCr thin film resistors, at least one of which has aprecisely determined TCR, in an integrated circuit structure.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a practical method andintegrated circuit structure for providing various combinations of thesame or different high or low sheet resistances and the same ordifferent TCRs for two or more thin film resistors, each on a differentlayer.

It is another object of the invention to provide a practical techniquefor providing a thin film resistor structure that can be used to offsetthe TCR of integrated circuit elements in which the TCR is not easilyadjustable during integrated circuit manufacture.

It is another object of the invention to provide a way of manufacturingmore stable thin film resistors in an integrated circuit process.

It is another object of the invention to provide an integrationtechnique for providing two accurate SiCr thin film resistors, at leastone of which has a precisely determined TCR, in an integrated circuitstructure.

It is another object of the invention to provide a thin film resistorhaving a large positive TCR in an integrated circuit which can be usedto offset a negative TCR of another circuit element in the integratedcircuit having a negative TCR.

It is another object of the invention to provide an integrationtechnique for providing two accurate SiCr thin film resistors havingdifferent sheet resistances and zero-value TCRs.

Briefly described, and in accordance with one embodiment, the presentinvention provides an integrated circuit structure including multiplethin film resistors of the same or different sheet resistances and thesame or different TCRs. The integrated circuit structure includes afirst oxide layer (2) formed on a semiconductor substrate (1), a firstthin film resistor (3) disposed on the first oxide layer (2), and asecond oxide layer (14) disposed over the first oxide layer (2) andfirst thin film resistor (3). A second thin film resistor (15) is formedon the second oxide layer (14) and a third oxide layer (16) is formedover the second thin film resistor (15) and the second oxide layer (14).Interconnect metallization elements (12A,B & 22A,B) formed on at leastone of the second (14) and third (16) oxide layers electrically contactthe circuit element (4), terminals of the first thin film resistor (3),and terminals of the second thin film resistor (15), respectively,through corresponding contact openings in at least one of the second(14) and third (16) oxide layers. In the described embodiments, at leastone of the first (3) and second (15) thin film resistors is composed ofone of the group including sichrome (SiCr) and tantalum nitride (TaN).

In one embodiment, some of the interconnect metallization elements arepart of a first metallization layer (Metal 1) formed on the third oxidelayer (30 in FIG. 19) for providing electrical connection to a terminalof the circuit element (4) through a contact opening in the first (2),second (5), and third (30) oxide layers, for providing electricalconnections to terminals of the second thin film resistor (15) throughcontact openings in the third oxide layer (30), and for providingelectrical contact to terminals of the first thin film resistor (3)through contact openings in the second (5) and third (30) oxide layers.The integrated circuit structure further includes a fourth oxide layer(14) on the first metallization layer (Metal 1) and the third oxidelayer (30), others of the interconnect metallization elements beingincluded in a second metallization layer (Metal 2) on the fourth oxidelayer (14) for providing electrical connections to various interconnectmetallization elements of the first metallization layer (Metal 1)through contact openings in the fourth oxide layer (14).

In another embodiment, an intermediate oxide layer (5) is formed on thefirst oxide layer (2) and the first thin film resistor (3), the secondoxide layer (14) being disposed on the intermediate oxide layer (5) andat least some of the interconnect metallization elements (12A,B,C). Someof the interconnect metallization elements are included in a firstmetallization layer (Metal 1) formed on the intermediate oxide layer (5)for providing electrical connection to a terminal of the circuit element(4) through a contact opening in the first (2) and intermediate (5)oxide layers and for providing electrical contact to terminals of thefirst thin film resistor (3) through contact openings in theintermediate oxide layer (5). Others of the interconnect metallizationelements are included in a second metallization layer (Metal 2) formedon the third oxide layer (16) for providing electrical connections toterminals of the second thin film resistor (15) through contact openingsin the third oxide layer (16) and for providing electrical connection tovarious interconnect metallization elements of the first metallizationlayer (Metal 1).

In the described embodiments, the first thin film resistor (3) can be afirst SiCr resistor having a first sheet resistance and a firsttemperature coefficient of resistance, and the second thin film resistor(15) can be a second SiCr resistor (15) having a second sheet resistanceand a second temperature coefficient of resistance. A vanadium silicidelayer (8) may be formed between the a metallization element of the firstmetallization layer (Metal 1) on the terminal of the circuit element (4)at the bottom of the contact opening through the first (2) and fourth(5) oxide layers for providing the electrical connection between themetallization element and the terminal of the circuit element (4).

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-11 schematically illustrate successive process steps in theformation of a first thin film resistor structure according to thepresent invention.

FIGS. 12-19 schematically illustrate successive process steps in theformation of a second thin film resistor structure according to thepresent invention.

FIG. 20 is a graph including three empirical curves showing the changein sheet resistance Rs and TCR of thin film SiCr layers of variousthicknesses as a function of durations of anneal cycles to which thelayers are subjected.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1-11 illustrate a sequence of processing operations according to afirst embodiment of the invention for fabricating a first thin filmresistor structure including two thin film resistors composed ofdifferent thin film material having the same or different sheetresistances and also having the same or different TCRs.

FIG. 1 shows a starting silicon substrate 1 having a standard pre-metaldielectric layer 2 including a first TEOS (tetraethylorthosilicate)layer on silicon substrate 1, a BPTEOS (Boron-Phosphorus TEOS) layer onthe first TEOS sublayer, and a second TEOS layer on the BPTEOS sublayer.A thin layer 3 of sichrome (SiCr) having a sheet resistance, typicallyin the range from 30 to 2000 ohms per square (based on previouslydeveloped curves of TCR versus sheet resistance for the particular SiCrdeposition process), has been deposited on the upper surface ofpre-metal dielectric layer 2. An anneal process has been performed toadjust the TCR of SiCr layer 3 to a desired (typically positive) value,and a conventional photoresist deposition, etching, and cleaning processhas been performed to define the shape of SiCr resistor 3. The TCRversus sheet resistance curves establish the anneal cycle that is neededto cause the TCR of SiCr layer 3 to increase along one of the TCR versusRs curves in FIG. 20 from a particular negative value to a desired(typically positive) target value. Conventional rapid thermal anneal(RTA) technology or conventional tube annealing can be used toaccomplish the annealing cycle.

FIG. 20 shows how anneal cycles affect the sheet resistance Rs and TCRof deposited SiCr layers of three different thicknesses. Specifically,FIG. 20 shows three TCR versus Rs curves for three deposited SiCr layersof 30, 50, and 120 Angstroms thickness. The dashed line labeled“Intrinsic” intersects the points of the three curves indicating the TCRin ppm (parts per million) and the Rs in ohms per square for the threedeposited SiCr layers before any annealing. The dashed line labeled“Anneal # 1” intersects the points of the three curves indicating theTCR in ppm (parts per million) and the sheet resistance Rs in ohms persquare of the three deposited layers after the three SiCr layers havebeen subjected to a first anneal cycle of a predetermined time (e.g., 30minutes) at a predetermined temperature, which typically is greater than475 degrees Centigrade. The dashed line labeled “Anneal # 2” intersectsthe points of the three curves indicating the TCR and the Rs of thethree deposited layers after the three SiCr layers have been subjectedto a second anneal cycle of a predetermined time, and the dashed linelabeled “Anneal #3” intersects the points of the three curves indicatingthe TCR and the Rs of the three deposited layers after the three SiCrlayers have been subjected to a third anneal cycle of a predeterminedtime.

Initially the TCR of the deposited SiCr layer is usually negative, andits TCR crosses zero and becomes positive with continued annealing. Thecurves of FIG. 20 show that SiCr layers can be annealed so as to achievezero or positive values of TCR, depending on the amount of time andtemperature at which the deposited SiCr film is annealed. The thinnerSiCr layers tend to be more sensitive to further annealing.

It is important that the sheet resistance and TCR of bottom SiCr film 3is subjected to thermal cycles in accordance with curves such as thoseshown in FIG. 20 prior to deposition of an interconnect metallizationlayer and also prior to deposition of another SiCr (or othercomposition) resistive layer, and it is preferable that no subsequentlydeposited thin film layer require annealing at temperatures that wouldchange the TCR and sheet resistance of SiCr layer 3. Also, the presenceof interconnect metallization deposited after the annealing of SiCrlayer 3 would make determination of subsequent thermal cycles of thekind needed to adjust sheet resistance and TCR of a subsequently formedSiCr layer to desired target values much more difficult.

In accordance with one aspect of the present invention, the TCR of thebottom SiCr layer 3 is adjusted by suitable annealing before performingany further high temperature steps or metallization steps in theintegrated circuit manufacturing process.

Referring to FIG. 2, a standard TEOS barrier layer 5 is formed on theupper surfaces of pre-metal dielectric layer 2 and SiCr resistor layer3. After performing a photoresist procedure to define the locations ofcontact openings to expose electrodes/terminals of various otherelements 4, such as transistors and diffused resistors (not shown) thatare previously formed in silicon substrate 1, various contact openings 7are etched through TEOS layer 5 and pre-metal dielectric layer 2 asillustrated.

Referring to FIG. 3, a vanadium deposition is performed on the exposedupper surface of the wafer, including the bottoms of contact openings 7.The wafer then is subjected to a suitable temperature to cause formationof vanadium silicide layers 8 at the bottoms of the contact openings 7.Unreacted vanadium is removed from the rest of the exposed wafer surfaceto produce the structure as illustrated in FIG. 3. (Note that palladiumsilicide could be formed instead of vanadium silicide.)

Referring to FIG. 4, a suitable photoresist operation and oxide etchingprocedure is performed to define contact openings 10A and 10B in TEOSbarrier layer 5 to expose the contact areas of SiCr resistor 3.

Referring to FIG. 5, a first metallization layer, referred to as the“Metal 1” layer is deposited on the exposed surface of the wafer. TheMetal 1 layer fills the contact openings 7, making good electricalcontact to the vanadium silicide layer(s) 8, and also fills the SiCrresistor via openings 10A and 10B to electrically contact both ends ofSiCr resistor 3. The Metal 1 layer also contacts the above-mentionedelectrodes and/or terminals of transistors, diffused resistors, etc.in/on silicon substrate 1 exposed by various contact openings 7. Asuitable photoresist, metallization etching, and cleaning procedureproduces the structure shown in FIG. 5.

Referring to FIG. 6, the next step is to deposit a “TEOS liner” sublayerportion (not shown) of an oxide/dielectric layer 14 over the exposedwafer surface including the exposed oxide surface area and the Metal 1surface area. Oxide layer 14 also includes a “FOx” spin-on sublayerlayer on the above-mentioned TEOS liner sublayer to achieve a degree ofplanarization. The term “FOx” refers to “flowable oxide”, is a trademarkof Dow Corning, and is composed of hydrogen silsesquioxane (HSiO^(3/2)).An annealing of the structure is performed in the presence of nitrogengas or other suitable ambient. Finally, layer 14 is completed bydepositing a TEOS “cap” sublayer on the FOx spin-on sublayer.

Referring to FIG. 7, the next step is to deposit a “high precision”second SiCr layer 15 having a sheet resistance which may beapproximately 1000 ohms per square (although it may be in the range ofapproximately 30-2000 ohms per square) on the exposed surface of layer14. The second SiCr layer 15 also has a target TCR value.

The second-deposited SiCr layer 15 typically is the one with highersheet resistance, and the first-deposited SiCr layer 3 typically has arelatively low sheet resistance. The first-deposited SiCr layer 3 ispreferably the one which is annealed as previously described to increaseits TCR and to decrease its sheet resistance to desired target values,and the second-deposited SiCr layer 15 with high sheet resistancepreferably is deposited with high precision sheet resistance and a TCRvalue of zero. If second-deposited SiCr layer 15 were to be annealed ata substantially high temperature for a substantially long duration, thesame annealing process would also result in difficult-to-control changesin the sheet resistance and TCR of the first-deposited SiCr layer 3, andin this usually would be undesirable.

Referring to FIG. 8, the next step is to deposit a TEOS layer 16 on theexposed surface areas of oxide layer 14 and SiCr resistor layer 15,followed by a photoresist and etching procedure to define the locationsand sizes of various via openings 18A and 18B extending down throughoxide layer 16 and through oxide layer 14 to expose surfaces of variousMetal 1 conductors 12A and 12B, as shown.

Referring to FIG. 9, the next step is to perform a photoresist andetching procedure to define the sizes and locations of via openings 20Aand 20B through oxide layer 16 to expose the contact areas at the endsof SiCr resistor layer 15, as shown. Next, as shown in FIG. 10, a “Metal2” metallization layer is deposited on the exposed wafer surface,extending through the contact openings 18A and 18B to electricallycontact the exposed surfaces of Metal 1 conductors 12A and 12B,respectively, and also extending through resistor contact or viaopenings 20A and 20B to contact the ends of SiCr resistor 15, as shown.A photoresist and etching procedure defines the sizes and shapes of theMetal 2 conductors 22A and 22B as shown in FIG. 10.

The next step is to deposit (or spin on) a protective passivation layer24, which may be SiON (silicon oxynitride), followed by a photoresistand etching procedure to define bonding pad openings such as bonding padopening 26. This results in the integrated circuit thin film resistorstructure 28A shown in FIG. 11.

The described embodiments of the invention provide the design engineerwith a zero-TCR thin film resistor as an available circuit element. Theinvention also can provide to the design engineer a positive TCRresistor which can be used to offset negative TCs of other componentssuch as bipolar and MOS transistors, diffused resistors, etc. Thisallows the design engineer to provide high precision “upper” levelresistors such as resistor 15 which do not need to be adjusted or“tuned”, and in the same integrated structure, to also provide otherresistors such as “lower” level SiCr resistor 3 which can be adjusted or“tuned” by thermal annealing procedures to achieve the desired TCR. Theresulting high precision resistor structure can be used at any nodewithin a circuit requiring a stable resistor.

In a second embodiment of the invention, two different thin film SiCrlayers of the same or different sheet resistances and different TCRs areintegrated into a structure in which the two different SiCr layers canbe interconnected by only the Metal 1 level of interconnectmetallization, whereas in the embodiment of FIGS. 1-11, the second SiCrresistor 15 can only be electrically contacted by means of the Metal 2interconnect metallization layer.

The same wafer structure with SiCr layer 3 as shown in FIG. 1 is thestarting point in making the second embodiment of the invention. FIGS.12-19 illustrate a sequence of further processing operations accordingto the second embodiment of the invention for fabricating a thin filmresistor structure including two thin film resistors including the sameor different sheet resistances and the same or different TCRs, with theability to adjust the TCR of the lower SiCr layer 3 so as to not affectthe subsequently formed upper SiCr layer 15. Referring to FIG. 12, thefirst TEOS barrier layer 5 is formed on the upper surface of pre-metaldielectric layer 2 and SiCr resistor layer 3. The next step is todeposit the “high precision” second SiCr layer 15 having a sheetresistance in the range of approximately 30-2000 ohms per square and aprecise target value of TCR on the exposed surface of first TEOS barrierlayer 5. After performing a photoresist procedure to define thelocations of contact openings to expose terminals of various otherelements formed in silicon substrate 1, such as transistors and diffusedresistors (not shown), various contact openings 7 are etched throughTEOS layer 5 and pre-metal dielectric layer 2 as illustrated.

If desired, a vanadium deposition (as previously described withreference to FIGS. 3 and 4) could also be performed between the stepsfor providing the structures shown in FIGS. 13 and 14 to form vanadiumsilicide layers (such as vanadium silicide layer 8 in FIG. 4 on thebottoms of the contact openings 7. This would be done before etching ofcontact openings 10A,B or 20A,B.

Referring to FIG. 14, a suitable photoresist operation and oxide etchingprocedure is performed next to define contact openings 10A and 10B infirst TEOS barrier layer 5, and to define via openings 20A and 20B insecond TEOS barrier layer 30 and first TEOS barrier layer 5 to exposecontact areas of SiCr resistors 15 and 3, respectively, as shown.

Referring to FIG. 15, a “Metal 1” metallization layer is deposited onthe exposed surface of the wafer, filling the contact openings 7 to makeelectrical contact to electrode/terminals of various transistors,diffused resistors etc. (not shown) previously formed in region 4 ofsilicon substrate 1. The Metal 1 layer also fills the SiCr resistor viaopenings 10A and 10B to electrically contact both terminals of SiCrresistor layer 3 and also fills the contact openings 20A and 20B toelectrically contact both terminals of SiCr resistor 15. A suitablephotoresist, metallization etching, and cleaning procedure results inthe structure as shown in FIG. 15.

Referring to FIG. 16, the next step is to deposit a “TEOS liner”sublayer (not shown) of layer 14 over the exposed wafer surfaceincluding the exposed oxide surface area and the Metal 1 surface area.Layer 14 also includes a FOx spin-on sublayer layer on the TEOS linersublayer to achieve a degree of planarization. An anneal in the presenceof nitrogen gas is performed. Finally, layer 14 is completed bydepositing a TEOS “cap” sublayer on the FOx spin-on sublayer layer.

Referring to FIG. 17, the next step is to perform a photoresist andetching procedure to define the locations and sizes of various viaopenings 18A and 18B extending down through layer 16 and layer 14 toexpose surfaces of various Metal 1 conductors 12A and 12B, as shown.

Next, as shown in FIG. 18, a second metallization “Metal 2” layer 22 isdeposited on the exposed wafer surface, extending through the contactopenings 18A and 18B to electrically contact the exposed surface areasof various Metal 1 conductors such as conductors 12A and 12B,respectively. After a photoresist and etching procedure, the variousMetal 2 conductors 22 are defined generally as shown in FIG. 18.

The next step is to form a protective passivation layer 24, which may beSiON, followed by a photoresist and etching procedure to define bondingpad openings such as bonding pad opening 26. This results in theintegrated circuit thin film resistor structure 28B as shown in FIG. 11.

As in the embodiment of FIGS. 1-11, the first-deposited SiCr resistor 3is integrated into the process, and then is annealed at highertemperatures (in accordance with empirical curves such as the ones shownin FIG. 20) before performing any additional high-temperature or othersubstantial processing steps, in order to reduce the sheet resistance Rsand shift the TCR of the SiCr resistor 3 to a more positive targetvalue. (The annealing of SiCr resistor 3 also tends to improve itsabsolute stability.) The second-deposited, typically near-zero-TCR SiCrresistor 15 then is integrated at the same Metal 1 layer (as in FIGS.1-11) or at the Metal 2 level in the integration (as in FIGS. 12-19).

The embodiment of FIGS. 12-19 can be advantageous when used inconjunction with a process that includes only a single layer of maininterconnect metallization. This process/structure can be added tovarious integrated circuit processes which include only a singlemetallization layer, in cases wherein the pre-existing integratedcircuit process can tolerate the annealing temperatures required for theSiCr layer 3.

It should be appreciated that lower resistor 3 and/or upper resistor 15could be tantalum nitride (TaN). If lower resistor 3 is composed of TaN,then the above described additional annealing might not be necessary,because the adjustment of the TCR and sheet resistance Rs of a TaNresistor 3 could be accomplished by controlling the amount of othercomponents, such as nitrogen, in the tantalum nitride film 3 as it isdeposited. The sheet resistance for TaN resistors in this applicationcould be in approximately the same 30 to 2000 ohms per square range forTaN thin film resistors as for SiCr thin film resistors.

An advantage of the invention is that it allows integration of ahigh-TCR component into a high precision integrated circuit process. Thehigh-TCR component can be used to offset a negative TC of othercomplements/circuits on the die.

While the invention has been described with reference to severalparticular embodiments thereof, those skilled in the art will be able tomake various modifications to the described embodiments of the inventionwithout departing from its true spirit and scope. It is intended thatall elements or steps which are insubstantially different from thoserecited in the claims but perform substantially the same functions,respectively, in substantially the same way to achieve the same resultas what is claimed are within the scope of the invention. Anotherapplication of the invention could be to deposit upper and lower thinfilm resistors, where all of the laser-trimmable resistors are providedon the upper level to make them accessible for laser trimming. Othersilicide layers, such as cobalt silicide or nickel silicide, could beused instead of vanadium silicide.

1. An integrated circuit structure including multiple thin filmresistors having the same or different sheet resistances and the same ordifferent TCRs (temperature coefficients of resistance), comprising: (a)a first oxide layer disposed on a semiconductor substrate having acircuit element therein; (b) a first thin film resistor disposed on thefirst oxide layer and a second oxide layer disposed over the first oxidelayer and the first thin film resistor; (c) a second thin film resistordisposed on the second oxide layer and a third oxide layer disposed overthe second thin film resistor and the second oxide layer; and (d)interconnect metallization elements disposed on at least one of thesecond and third oxide layers and contacting the circuit element,terminals of the first thin film resistor, and terminals of the secondthin film resistor, respectively, through corresponding contact openingsin at least one of the second and third oxide layers.
 2. The integratedcircuit structure of claim 1 wherein at least one of the first andsecond thin film resistors is composed of one of the group includingsichrome (SiCr) and tantalum nitride (TaN).
 3. The integrated circuitstructure of claim 1 wherein some of the interconnect metallizationelements are part of a first metallization layer formed on the thirdoxide layer for providing electrical connection to a terminal of thecircuit element through a contact opening in the first, second, andthird oxide layers, for providing electrical connections to terminals ofthe second thin film resistor through contact openings in the thirdoxide layer, and for providing electrical contact to terminals of thefirst thin film resistor through contact openings in the second andthird oxide layers, the integrated circuit structure further including afourth oxide layer on the first metallization layer and the third oxidelayer, others of the interconnect metallization elements being includedin a second metallization layer on the fourth oxide layer for providingelectrical connections to various interconnect metallization elements ofthe first metallization layer through contact openings in the fourthoxide layer.
 4. The integrated circuit structure of claim 1 including afourth oxide layer disposed on the first oxide layer and the first thinfilm resistor, the second oxide layer being disposed on the fourth oxidelayer and at least some of the interconnect metallization elements. 5.The integrated circuit structure of claim 4 wherein some of theinterconnect metallization elements are included in a firstmetallization layer disposed on the fourth oxide layer for providingelectrical connection to a terminal of the circuit element through acontact opening in the first and fourth oxide layers and for providingelectrical contact to terminals of the first thin film resistor throughcontact openings in the fourth oxide layer, and wherein others of theinterconnect metallization elements are included in a secondmetallization layer disposed on the third oxide layer for providingelectrical connections to terminals of the second thin film resistorthrough contact openings in the third oxide layer and for providingelectrical connection to various interconnect metallization elements ofthe first metallization layer.
 6. The integrated circuit structure ofclaim 5 including a metal silicide layer between the a metallizationelement of the first metallization layer on the terminal of the circuitelement at the bottom of the contact opening through the first andfourth oxide layers for providing the electrical connection between themetallization element and the terminal of the circuit element.
 7. Theintegrated circuit structure of claim 4 wherein the first thin filmresistor is a first SiCr resistor having a first sheet resistance and afirst temperature coefficient of resistance, and wherein the second thinfilm resistor is a second SiCr resistor having a second sheet resistanceand a second temperature coefficient of resistance.
 8. The integratedcircuit structure of claim 7 wherein the first sheet resistance has avalue and the range from 30 to 2000 ohms per square and the firsttemperature coefficient of resistance has a positive value, and whereinthe second sheet resistance has a value in the range from 30 to 2000ohms per square and the second temperature coefficient of resistance hasa negative value.
 9. The integrated circuit structure of claim 1 whereinthe first thin film resistor is a first SiCr resistor having a firstsheet resistance and a first temperature coefficient of resistance, andwherein the second thin film resistor is a second SiCr resistor having asecond sheet resistance and a second temperature coefficient ofresistance.
 10. The integrated circuit structure of claim 9 wherein thefirst sheet resistance has a value in the range from 30 to 2000 ohms persquare and the first temperature coefficient of resistance has apositive value, and wherein the second sheet resistance has a value inthe range from 30 to 2000 ohms per square and the second temperaturecoefficient of resistance has a negative value.
 11. The integratedcircuit structure of claim 1 wherein the second oxide layer is a firstTEOS barrier layer and the third oxide layer is a second TEOS barrierlayer formed directly on the second oxide layer and the first thin filmresistor.